Return-Path: X-Original-To: rtcweb@ietfa.amsl.com Delivered-To: rtcweb@ietfa.amsl.com Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 7FA9411E80E9 for ; Mon, 29 Jul 2013 10:43:02 -0700 (PDT) X-Virus-Scanned: amavisd-new at amsl.com X-Spam-Flag: NO X-Spam-Score: -1.699 X-Spam-Level: X-Spam-Status: No, score=-1.699 tagged_above=-999 required=5 tests=[BAYES_00=-2.599, HTML_MESSAGE=0.001, J_CHICKENPOX_15=0.6, MIME_8BIT_HEADER=0.3, NO_RELAYS=-0.001] Received: from mail.ietf.org ([12.22.58.30]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 9mbkvzzBeiCS for ; Mon, 29 Jul 2013 10:43:01 -0700 (PDT) Received: from mail-we0-x232.google.com (mail-we0-x232.google.com [IPv6:2a00:1450:400c:c03::232]) by ietfa.amsl.com (Postfix) with ESMTP id 4BF3F21F9A3D for ; Mon, 29 Jul 2013 10:43:00 -0700 (PDT) Received: by mail-we0-f178.google.com with SMTP id u57so4154970wes.23 for ; Mon, 29 Jul 2013 10:42:59 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; bh=bNEc+Kqg0rzAjGb0JSjFDHyNYm+2V81Rj3X0jwlepsY=; b=TfgF5lFa00XqHs0Sx6yVbjNcqwfBxaR62C4POPrxnOA5Cmh0O/55SZpgN/pOhyeA4I CyuPZJB+N2ZO6i93ks6JxbGHvCa3YEVyTQm0rlOA7QW2xdImwAzPhyjVqgnQRe1iE23z yEbEw42XCSRhT4kouIRP80dBBUWws7jZ7P5664zSO9G3E0GtIYd2U3/orDTAcKa2wGjy DQ9LWpyjVIEHMUXJPkilg17Ox/g/HQ0bGrDNgbS/jj69WYC5H09cwfW/wBZOd7v3rC38 EoRza/CZqoDOfqubyB9CPSUx62PCwTF3RJ+uFS90priWrLcxl0uuba2kWddtgYrprKGA xIfg== MIME-Version: 1.0 X-Received: by 10.180.9.235 with SMTP id d11mr7860537wib.35.1375119779439; Mon, 29 Jul 2013 10:42:59 -0700 (PDT) Received: by 10.195.13.75 with HTTP; Mon, 29 Jul 2013 10:42:59 -0700 (PDT) Received: by 10.195.13.75 with HTTP; Mon, 29 Jul 2013 10:42:59 -0700 (PDT) In-Reply-To: References: Date: Mon, 29 Jul 2013 19:42:59 +0200 Message-ID: From: "piranna@gmail.com" To: =?ISO-8859-1?Q?I=F1aki_Baz_Castillo?= Content-Type: multipart/alternative; boundary=001a11c2195afa347f04e2aa0538 Cc: rtcweb@ietf.org, public-webrtc Subject: Re: [rtcweb] SDP is not suitable for WebRTC X-BeenThere: rtcweb@ietf.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Real-Time Communication in WEB-browsers working group list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 29 Jul 2013 17:43:03 -0000 --001a11c2195afa347f04e2aa0538 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable No, this scenario seems more of a beta or maybe an alpha than a polished 1.0 version. El 29/07/2013 19:34, "I=F1aki Baz Castillo" escribi=F3: > Hi, I initiated a thread [*] about Plan-Unified and multiple m lines, > but it was moved to MMUSIC maillist (don't know why since it is about > WebRTC applications design): > > http://www.ietf.org/mail-archive/web/mmusic/current/msg11966.html > > Sorry for the cross-posting but at this point I'm a bit lost and do > not know which is the appropriate group for my concern. > > > > So my concern is: > > > - Web application with a SIP over WebSocket client running in the web. > > - The web user is provided with a conference SIP URI in which there > are *already* 8 participants (5 of them emitting audio and video and 3 > just emitting audio). > > - The user calls, from his webphone, to the given URI to join the > conference. > > > > Let's imagine that the JS app knows the number of participant in the > conference. > Let's imagine my browser have mic and webcam. > > > > QUESTION: > > How can my browser join the conference without requiring SDP > renegotiation from the server and, at the same time, being able to > send audio/video and receive audio/video from others (different tracks > / m=3Dlines)? > > > > > "SOLUTIONS": > > > > 1) > > I tell my browser to generate a SDP offer with: > > - 1 send/receive m=3Daudio line. > - 7 recvonly m=3Daudio line. > - 1 send/only m=3Dvideo line. > - 4 recvonly m=3Dvideo line. > > (Obviously this is a joke) > > > > 2) > > SDP seems to allow that the offer and the answer have different number > of m lines (I'm not aware of that but I believe that SDP can do > "everything"). So my browser generates a SDP offer with 1 m=3Daudio line > and 1 m=3Dvideo line, and the server replies with 8 m=3Daudio lines and 4 > m=3Dvideo lines. > > Will my browser understand such a SDP answer with more m lines than > its generated offer? I assume NOT. > > > > 3) > > My browser generates a SDP offer with 1 m=3Daudio line and 1 m=3Dvideo > line and the server too. And later the server sends re-INVITE with all > the m lines. > > Oppss, SDP renegotiation... > > > > > SDP is bad for WebRTC. SDP is good for legacy symmetric communications > in which there is a single-track audio communication and, of course, > both endpoints emit audio. But SDP is bad for modern RTC protocols in > which an endpoint can emit tons of tracks to a single endpoint. > > > Do we really want this for WebRTC 1.0 ? > > > -- > I=F1aki Baz Castillo > > > --001a11c2195afa347f04e2aa0538 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable

No, this scenario seems more of a beta or maybe an alpha tha= n a polished 1.0 version.

El 29/07/2013 19:34, "I=F1aki Baz Castillo&= quot; <ibc@aliax.net> escribi=F3= :
Hi, I initiated a thread [*] about Plan-Unified and multiple m lines,
but it was moved to MMUSIC maillist (don't know why since it is about WebRTC applications design):

http://www.ietf.org/mail-archive/web/mmusic/current/ms= g11966.html

Sorry for the cross-posting but at this point I'm a bit lost and do
not know which is the appropriate group for my concern.



So my concern is:


- Web application with a SIP over WebSocket client running in the web.

- The web user is provided with a conference SIP URI in which there
are *already* 8 participants (5 of them emitting audio and video and 3
just emitting audio).

- The user calls, from his webphone, to the given URI to join the conferenc= e.



Let's imagine that the JS app knows the number of participant in the co= nference.
Let's imagine my browser have mic and webcam.



QUESTION:

How can my browser join the conference without requiring SDP
renegotiation from the server and, at the same time, being able to
send audio/video and receive audio/video from others (different tracks
/ m=3Dlines)?




"SOLUTIONS":



1)

I tell my browser to generate a SDP offer with:

=A0 - 1 send/receive m=3Daudio line.
=A0 - 7 recvonly m=3Daudio line.
=A0 - 1 send/only m=3Dvideo line.
=A0 - 4 recvonly m=3Dvideo line.

(Obviously this is a joke)



2)

SDP seems to allow that the offer and the answer have different number
of m lines (I'm not aware of that but I believe that SDP can do
"everything"). So my browser generates a SDP offer with 1 m=3Daud= io line
and 1 m=3Dvideo line, and the server replies with 8 m=3Daudio lines and 4 m=3Dvideo lines.

Will my browser understand such a SDP answer with more m lines than
its generated offer? I assume NOT.



3)

My browser generates a SDP offer with 1 m=3Daudio line and 1 m=3Dvideo
line and the server too. And later the server sends re-INVITE with all
the m lines.

Oppss, SDP renegotiation...




SDP is bad for WebRTC. SDP is good for legacy symmetric communications
in which there is a single-track audio communication and, of course,
both endpoints emit audio. But SDP is bad for modern RTC protocols in
which an endpoint can emit tons of tracks to a single endpoint.


Do we really want this for WebRTC 1.0 ?


--
I=F1aki Baz Castillo
<ibc@aliax.net>

--001a11c2195afa347f04e2aa0538--